Three years after the Deepwater Horizon oil spill, researchers are beginning to get a better idea of the long-term impacts for coastal ecosystems. A research team from LSU, University of California, Davis and Clemson University, has found that exposure of Gulf killifish embryos to sediments from oiled locations caused cardiovascular defects, delayed hatching and reduced overall hatching success. To date, the group’s research has used this popular environmental indicator species to determine the extent of exposure of field-caught fish, using these fish as a ‘canary in the coal mine.’

“Although the Deepwater Horizon oil spill has passed the attention of most of the nation, our data warn of developmental abnormalities in coastal fish that should be further investigated,” said Fernando Galvez, LSU associate professor in the Department of Biological Sciences and one of the principle investigators on the supporting grant. “We are finding that embryos exposed to oiled Louisiana sediments are hatching at lower frequencies and are showing developmental abnormalities, and that embryos that do go on to hatch successfully are smaller and listless.”

These findings, published in the scientific journal “Environmental Science and Technology,” are part of an ongoing collaborative effort to track the impacts of the Deepwater Horizon oil spill on Gulf killifish populations in areas of Louisiana that received landfall of oil.

“Other species that share similar habitats with the Gulf killifish [such as redfish, speckled trout, flounder, blue crabs, shrimp and oysters] are at risk of similar effects. What is currently unknown is the capacity of affected populations to buffer or absorb the impacts of these types of developmental effects,” said Andrew Whitehead, UC Davis assistant professor of environmental toxicology and co-principle investigator and co-author on the paper. “However, our research has linked exposure to oil to the molecular responses that initiate toxic effects and now to negative impacts on the well-being of an important ecological indicator species – our ‘canary in the coal mine.’”

Benjamin Dubansky, a recent LSU Ph. D. was first author on the manuscript. Co-authors on the study include Galvez, Whitehead and Charles D. Rice, professor in the Department of Biological Sciences at Clemson University.

“Adult fish collected from heavily oiled locations in Louisiana marshes showed evidence of exposure to crude oil long after the visible oil had disappeared from view, and when Gulf killifish embryos were exposed to sediments collected from the most oiled location, their overall hatching success was significantly reduced, there was a time delay in hatching, and this was associated with developmental heart defects in these fish,” said Dubansky, who is beginning a post-doctoral position in Warren Burggren’s lab in the Developmental Integrative Biology Cluster at the University of North Texas, where he will to continue his work on the effects of environmental stressors on vertebrate development. “The developmental deformities found are textbook effects that we see when fish are exposed to the toxicants in crude oil, and indicate that the developmental success of these fish in the field may be compromised.”

These researchers have tracked the impact of the oil on killifish since the Deepwater Horizon spill occurred in April 2010, even testifying before the House of Representatives’ Committee on Natural Resources (http://www.lsu.edu/ur/ocur/lsunews/MediaCenter/News/2011/10/item37793.html). Galvez and Whitehead continue to study the impact of the oil spill, and recently received federal funding from the National Institute of Environmental Health Sciences and the National Science Foundation to characterize further the long-term consequences of sub-lethal crude oil exposure in killifish embryos, and to get a better handle on multi-generational effects that have the potential to adversely affect fish populations and communities in Louisiana’s coastal marsh.